Lago di Nemi

The Lago di Nemi (known in English as Lake Nemi or Diana's Mirror) is a volcanic lake in the Lazio region of Italy.

History
Roughly 30 kilometers south of Rome, this small volcanic lake is named for the largest town in its vicinity, Nemi. It is most renowned for its massive sunken Roman ships, the larger of which are thought to have been elaborate floating palaces of the 1st century. Some of the technology found on these ships was believed to have been invented only recently, including complex heating systems and plumbing for baths.